The following invention relates to a method and apparatus for the precise implantation of surgical instruments, such as needles, in body tissue along a predetermined linear path.
Certain types of surgery or treatment of disease in the human body require the implantation of surgical instruments, such as needles or tubes, in body tissue along a predetermined path. For example, one method used in the treatment of breast cancer involves the irradiation of a tumor within the breast by the implantation of radioactive iridium seeds. These seeds are implanted within and around the tumor location by forcing needles through the breast tissue and using these needles to pull thin nylon tubes along the needle track into the breast. These tubes provide a pathway for inserting strings of iridium seeds. In order to effect this treatment, however, it is necessary to implant the iridium bearing tubes at precise locations within the body tissue. Moreover, in order to avoid injury to muscle tissue the needles used to implant the surgical tubes should follow a predetermined path which does not pass through such tissue.
Body tissue, however, especially in the region of the breast, is difficult to implant in this manner because of its irregular contour and the tendency of the tissue to change contour when pressure is applied. These problems are aggravated further by the fact that for this type of treatment, a plurality of needles must be implanted at predetermined locations with respect to the tumor.
These locations may be determined by viewing Computerized Axial Tomography scans and X-rays taken of the tissue, and from the scans and X-rays the entry points of the needles may be determined. Once the location for the entry point of each of these needles is chosen it then becomes necessary to insure that the path followed by the needle will result in placing the iridium bearing tubes at the proper location. Thus, although the precise location of the tumor within the body tissue can be determined by standard radiological methods, the actual planning of the path through the body tissue and the physical implementation thereof remain a problem in this type of surgery.
In the past, systems have been proposed for locating a precise point wherein the body through a combination of stereotactic methods and radiology. For example, a three dimensional stereotactic device for use in neurosurgery is shown in the Hainault patent U.S. Pat. No. 3,508,552. In Hainault, multiple pairs of parallel grids each containing a plurality of apertures are loaded with solid metal rods. The function of the parallel grids and the rods inserted therein is to provide a reference for X-rays taken of the brain. By knowing the position of the grids relative to the cranium, the precise location of the tumor may be determined from the X-rays. A similar device is shown in the Perry patent, U.S. Pat. No. 4,341,220, in which a three dimensional frame is fitted over the cranium of the patient. The frame has three plates all of which have a plurality of slots of differing length to be used as a reference against which to measure an image of a slice of the brain as would be obtained from a CAT scan.
These devices, however, are for locating a point inside the body, and not for determining the linear path of a surgical instrument to be inserted through body tissue. Moreover, neither would be suitable for this purpose. Although the Perry device shows plates having apertures, one on each side of the body tissue to be examined, the apertures are elongate slots and are not adapted to correspond with one another so as to define a straight linear path through body tissue. In Hainault, the parallel plates do contain corresponding matrices of apertures, however, both are located on the same side of the body tissue. It is impossible to determine using the Hainault device, where the exit point of an implanted needle would be so as to define a linear path.
In the treatment of tumors as described above, it is necessary not only to determine a linear path through body tissue by designating entry and exit points on the surface thereof, it is also necessary to physically implant the tubes within the body that will deliver the necessary medication. Devices have been proposed for driving needles through body tissue, but all suffer from the same defect. The problem with such devices is that they are not capable of driving a needle along a predetermined path. In these devices precise placement of the needles depends upon eye-hand coordination. Two examples of such devices are shown in the U.S. patents to Moore, U.S. Pat. No. 4,086,914 and Walchle U.S. Pat. No. 3,913,584. The Walchle device is a trigger actuated implantation device and the Moore device is actuated by twisting a handle in stepwise fashion. Neither device provides any means for determining the path through the body tissue that the needle will take.
What is needed, therefore, is a device capable of planning a path or a plurality of paths through body tissue for implantation needles or surgical instruments, and also a device capable of implanting a needle through the body tissue capable of following this predetermined path. The device must be capable of working with any body tissue regardless of its contour and deformability.